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Search Results: 1 - 10 of 60009 matches for " X.Y. "
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Size Dependence of Structures and Properties of Magnetic Materials
Q. Jiang and X.Y. Lang
The Open Nanoscience Journal , 2007, DOI: 10.2174/1874140100701010032]
Abstract: Due to the involvement of high portion of atomic coordination imperfection in surfaces and interfaces, the properties of magnetic nanocrystals dramatically differ from that of the corresponding bulk counterparts, which have led to a surge in both experimental and theoretical investigations in the past decades. This review summarizes the studies for these size-dependent magnetic properties, and additional thermal or phase stabilities, and mechanical properties. To interpret the above phenomena, a thermodynamic model for the size dependence and interface dependences of these properties is described, which is based on Lindemann' s criterion for melting, Mott's expression for the vibrational melting entropy, and Shi's model for the size-dependent melting temperature. The model without any adjustable parameter is confirmed by a large number of experimental results, and helps us to understand the structures and properties of the magnetic nanocrystals. Moreover, other theoretical works on the above properties are also mentioned and commented.
Cytotoxicity of Marchantia convoluta leaf extracts to human liver and lung cancer cells
Xiao J.B.,Chen X.Q.,Zhang Y.W.,Jiang X.Y.
Brazilian Journal of Medical and Biological Research , 2006,
Abstract: The cytotoxicity of three extracts (petroleum ether, ethyl acetate and n-butanol) from a plant used in folk medicine, Marchantia convoluta, to human non-small cell lung carcinoma (H1299) and liver carcinoma (HepG2) cell lines was tested. After 72-h incubation of lung and liver cancer cell cultures with varying concentrations of extracts (15 to 200 μg/mL), cytotoxicity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and reported in terms of cell viability. The extracts that showed a significant cytotoxicity were subjected to gas chromatography-mass spectrometry analysis to identify the components. The ethyl acetate, but not the petroleum ether or n-butanol extract, had a significant cytotoxicity against lung and liver carcinoma cells with IC50 values of 100 and 30 μg/mL, respectively. A high concentration of ethyl acetate extract (100 μg/mL) rapidly reduced the number of H1299 cells. At lower concentrations of ethyl acetate extract (15, 30, and 40 μg/mL), the numbers of HepG2 cells started to decrease markedly. Gas chromatography-mass spectrometry analysis of the ethyl acetate extract revealed the presence of several compounds such as phytol (23.42%), 1,2,4-tripropylbenzene (13.09%), 9-cedranone (12.75%), ledene oxide (7.22%), caryophyllene (1.82%), and caryophyllene oxide (1.15%). HPLC analysis result showed that there were no flavonoids in ethyl acetate extract, but flavonoids are abundant in n-butanol extract. Further studies are needed regarding the identification, toxicity, and mechanism of action of active compounds.
Pressure dependence of elastic and dynamical properties of zinc-blende ZnS and ZnSe from first principle calculation
H.Y. Wang,J.Y. Cao,X.Y. Huang,J.M. Huang
Condensed Matter Physics , 2012,
Abstract: The density-functional theory (DFT) and density-functional perturbation theory (DFPT) are employed to study the pressure dependence of elastic and dynamical properties of zinc-blende ZnS and ZnSe. The calculated elastic constants and phonon spectra from 0 GPa to 15 GPa are compared with the available experimental data. Generally, our calculated values are overestimated with experimental data, but agree well with recent other theoretical values. The discrepancies with experimental data are due to the use of local density approximation (LDA) and effect of temperature. In this work, in order to compare with experimental data, we calculated and discussed the pressure derivatives of elastic constants, the pressure dependence of dynamical effect charge, and mode Grüneisen parameter at Γ.
Duodenal gastric metaplasia and Helicobacter pylori infection in patients with diffuse nodular duodenitis
Li, X.B.;Ge, Z.Z.;Chen, X.Y.;Liu, W.Z.;
Brazilian Journal of Medical and Biological Research , 2007, DOI: 10.1590/S0100-879X2006005000117
Abstract: whether the regression of gastric metaplasia in the duodenum can be achieved after eradication of helicobacter pylori is not clear. the aim of the present study was to investigate the relationship between h. pylori infection and gastric metaplasia in patients with endoscopic diffuse nodular duodenitis. eighty-six patients with endoscopically confirmed nodular duodenitis and 40 control patients with normal duodenal appearance were investigated. the h. pylori-positive patients with duodenitis received anti-h. pylori triple therapy (20 mg omeprazole plus 250 mg clarithromycin and 400 mg metronidazole, all twice daily) for one week. a control endoscopy was performed 6 months after h. pylori treatment. the h. pylori-negative patients with duodenitis received 20 mg omeprazole once daily for 6 months and a control endoscopy was performed 2 weeks after treatment. the prevalence of h. pylori infection was 58.1%, and the prevalence of gastric metaplasia was 57.0%. seventy-six patients underwent endoscopy again. no influence on the endoscopic appearance of nodular duodenitis was found after eradication of h. pylori or acid suppression therapy. however, gastric metaplasia significantly decreased and complete regression was achieved in 15/28 patients (53.6%) 6 months after eradication of h. pylori, accompanied by significant improvement of other histological alterations. only mild chronic inflammation, but not gastric metaplasia, was found in the control group, none with h. pylori infection in the duodenal bulb. therefore, h. pylori infection is related to the extent of gastric metaplasia in the duodenum, but not to the presence of diffuse nodular duodenitis.
Study on Population Genetic Structure of Liangshan Semi-Wool Sheep Using Microsatellite Markers
X.Y. Zhang,M.L. Zhou,X.H. Zhang,D.J. Wu
Pakistan Journal of Biological Sciences , 2008,
Abstract: To evaluate the genetic polymorphisms and to search for available molecular markers for Liangshan semi-wool sheep, 15 microsatellite markers of 187 samples were amplified by multiplex PCR. A total of 133 alleles were detected, with the number of alleles ranging from 6 (BM2830) to 15 (McM130), giving a mean No. of 8.87 alleles per locus. The total and mean effective allele No. were 64.29 and 4.29, respectively. The observed heterozygosity and expected heterozygosity were from 0.4486 (McM130) to 0.8877 (BMS1678) and 0.5704 (BMS0887) to 0.8373 (McM130), respectively. Mean observed heterozygosity and mean expected heterozygosity were 0.672 and 0.7536. Polymorphism information content values were from 0.5202 (BMS0887) to 0.8183 (McM130) and mean polymorphism information content of the 15 microsatellite loci was 0.7184. All 15 microsatellite loci were highly polymorphic, which showed that there were rich genetic polymorphisms at these detected microsatellite loci in Liangshan semi-wool sheep. Comparison of allele distributions among loci did not reveal consistent shapes. Distributions were centralized in some cases, whereas in others some kind of skewness was evident. Complex evolution at these loci is an important factor in the irregularity of microsatellite distributions.
Improving Handoff Call Handling in Future Mobile Networks with Location Tracking
A.N. Khan,X.J. Sha,X.Y. Zhang
Information Technology Journal , 2008,
Abstract: This study aims to incorporate location tracking of Mobile Terminals (MTs) for wireless resource management in contrast to existing schemes employing signal strength patterns and signal arrival timing characteristics. The incorporation of location information in Handoff (HO) call handling under heterogeneous traffic conditions can provide better efficiency and Quality of Service (QoS) guaranties. As present results confirm, a HO call handling scheme that takes into account the Received Signal Strength (RSS), speed and call type of users to prioritize HO requests reduces the blocking probability of HO calls, detects false HOs and provides better resource utilization performance as compared to Non Priority and First In First Out HO queuing schemes.
Fu Zi Prevent Extreme Cold Stress in Broilers Through Anti-Oxidative Activity
X.Y. Chen,S.H. Jin,R.S. Jiang,Z.Y. Geng
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2012.849.852
Abstract: Radix aconiti laterlis preparata (Fu Zi in Chinese), a Chinese traditional medicine has been widely used for Yang deficiency. Recent clinical studies have shown that Fu Zi could ameliorate stressed condition but the mechanisms underlying the anti-stress effect of Fu Zi remains unknown. In this study, researchers examined the effects of Fu Zi on the treatment of broilers exposed to Extreme Cold Stress (ECS). The levels of Nitric Oxide (NO) and creatine kinase in plasma were measured and Hsp70 mRNA expression in different tissues was analyzed. Broilers subjected to ECS exhibited increased NO content before 3 h and increased Hsp70 expression under a time and tissue-dependent manner. Biochemically, Fu Zi reversed ECS-induced increases in NO and Hsp70 mRNA and the results suggest that Fu Zi supplemented broilers kept an elevated plasma NO content through anti-oxidative activity during ECS.
Neuroendocrine Responses to Cold Stress in Chinese Indigenous Breeds from Different Latitude
X.Y. Chen,R.S. Jiang,H.C. Bai,Z.Y. Geng
Journal of Animal and Veterinary Advances , 2012, DOI: 10.3923/javaa.2011.3043.3047
Abstract: It is well established that stress is related to neurochemical and hormonal changes including alterations in adrenal and thyroid hormone levels. In the present study, thyroid axis and hypothalamic-pituitary-adrenal axis related hormomal, Triiodothyronine (T3), Thyroxine (T4), Thyroid-Stimulating Hormone (TSH), Adreno-Cortico-Tropic-Hormone (ACTH) and Thyroid Releasing Hormone (TRH) mRNA, ACTH mRNA changes during cold stress with different intensities were recorded in two Chinese indigenous breeds from different latitude. The results showed that Huainan partridge chicken from central China, showed obvious conversion in T3 and T4 under severe cold stress. Plasma TSH and pituitary TRH mRNA highly expressed over 12-24 h long time severe cold exposure. However, mild cold did not obviously affect those hormones mentioned above. In the Wenchang chicken which from south of China, severe and mild cold stress showed the same affection on the thyroid axis but not obvious on the adrenal axis. The results would further help the revealing of the mechanism of injury caused by cold stress and provide better controls for chicken from loss of cold stress in different areas.
Self-Assembly and Crystal Morphology of a Polysaccharide from the Loach
Y. Ding,X.Y. Shang,C.L. Xu,W.N. Niu
Science Journal Ubon Ratchathani University , 2010,
Abstract: In this paper, we investigated the self-assembly and crystalline feature of Misgurnusanguilliacaudatus polysaccharide (MAP) from the loach due to the theoretical and practicalimportance of MAP in biomedical engineering, biomaterials and environmental sciences etc. Theself-assembly and crystal morphology of MAP were observed under an atomic force microscope(AFM) and an optical microscope. The results indicted that the MAP crystalline processes two kindsof form unit, such as spindle-shaped rod and regular hexahedron. The basic form units can selfassembleto form particle-shaped or fiber-like assemblies at decades of micrometers. Furthermore,many regular holes at size of 100-200 nanometer scale distribute evenly on the micro-structuralsurface of leave-like assemblies. All of these results are valuable for the structure/function relationshipstudy of MAP and useful for application in biomedical materials.
Study on inclusion interaction of ibuprofen with Β-cyclodextrin derivatives
Song,L.T.; Jiang,X.Y.; Tang,K.W.; Miao,J. B.;
Latin American applied research , 2011,
Abstract: the inclusion interaction of ibuprofen with hydroxypropyl-β-cyclodextrin (hp-β-cd), hydroxyethyl-β-cyclodextrin (he-β-cd) and methyl-β-cyclodextrin (me-β-cd) was investigated by fluorescence spectroscopy. experimental conditions affecting the inclusion process, such as host molecule, hp-β-cd concentration and ph, were discussed in detail. the results suggested the formation of inclusion complexes with a stoichiometric ratio of 1:1 and hp-β-cd was more suitable to include neutral ibuprofen molecule. in addition, a phase solubility study was performed by mixing an excess amount of ibuprofen with aqueous solution containing increasing amount of β-cds using uv-vis. the results indicated that the solubility of ibuprofen was increased by inclusion with β-cd derivatives, and hp-β-cd was most efficient among the three β-cd derivatives. moreover, stable solid inclusion complexes were established and characterized by dsc.
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